Process for refining glyceride oils



Dec. 15, 1959 B H' THURMAN 2,917,525

PROCESS FOR REFINING GLYCERIDE OILS Filed Aug. 6. 1956 United StatesPatent PnocEsS FOR REFINiNG GLYCERIDE OILSv Benjamin H. Thurman, NewYork, N.Y., assigner to Benjamin Clayton, doing business as Retining,Unin- 4 corporated, Houston, Tex.

Application August 6, 1956, Serial No. 602,327

10 Claims. (Cl. Z50-425) This invention relates to a process andapparatus for refining glyceride oils, particularly animal and vegetableoils containing acidic impurities reactable with an alkali to produceseparable foots or soapstock. The acidic 'impurities of such oilsinclude, and are usually composed largely of, free fatty acids. Thesemust be removed in the refining operation to produce a marketable oil.Generally stated, the invention is concerned with the refining of suchoils by use of soda ash employed in such manner that carbon dioxide isevolved and removed before the oil-soapstock mixture is separated.

An early refining process mixed caustic soda with the oil to react withthe acidic impurities and produce soaps which were separable from theoil. Oil losses were relatively large in batch-type operations, and eventhe later continuous process produced undesirably high losses duelargely to the reaction between the caustic soda and the oil itself orto undesirably high entrainment of oil in the separated soapstock. f

More recently, soda ash refining processes have been used on many oils.Here aqueous solutions of soda ash have been mixed with the oil inamounts greatly in excess of those theoretically required to react theacidic impurities. Soda ash is a substantiallynon-saponifyingneutralizing agent but when it reacts with fatty acids orwith the reaction products of the two, carbon dioxide is liberated andinterferes with both the desired separation and the desired completionof the reaction.

To solve this problem, it has heretofore been common to employ the sodaash either in a dehydration-rehydra- -tion process or a high-excessprocess. In the former, an

amount of soda ash equal to 5-6 times the amount required to neutralizethe oil acidity is employed commercially. The soda ash solution is mixedwith the oil and the mixture is sent to a dehydration zone maintainedunder high vacuum to liberate and remove carbon dioxide and water. Thedehydrated mixture is then rehydrated and centrifuged. in thehigh-excess process the amount of soda ash is sufficient substantiallyto suppress the formation of carbon dioxide and sufficient to effect agood separation. Excesses of 68 times the amount required to neutralizeare commonly employed, often more. The oil-soapstock mixture is notdehydrated and rehydrated but is sent directly to a centrifuge.Sufficient excesses of soda ash are used to prevent gassing and toinsure that the neutralization of the free fatty yacids shall proceed tothe bicarbonate state.

In contradistinction to these prior processes, it has been found thatsubstantially improved results can be obtained by employing soda ash inamounts insufiicient to prevent liberation of carbon dioxide and thendegasifying the mixture before separation. Usually the amount of sodaash will be less than three times the amount theoretically required toneutralize the acidic impurities and preferably not more than abouttwice the amount thus theoretically required. While such small excesseshave been proposed in processes where soapstock separation was effectedunder substantial pressure yand at quite low temperatures in a closed orhermetically sealed centrifuge to avoid liberation of carbon dioxide,such centrifuges are costly and any low-excesses process employing themis sometimes erratic and fails to give the desired products andeconomies of the present process.

In the prior dehydration-rehydration and high-excess soda ash processes,the resulting soapstocks often present problems.A If such soapstocks areto be acidulated, the amount of sulfuric acid required is sometimesgreater than is economically justified. The present process permitssubstantial savings in this regard. In addition, such prior soapstocksare often so low in total fatty acids as not to be saleable,particularly when refining 4oils low in free fatty acids and high ormedium in gum content; also in refining degummed oils loW in free fattyacids. Additionally, such soapstocks often have undesirably highmoisture content. The present invention produces ini-- proved soapstocksof decreased total fatty acid content and moisture content-soapstockswhich are excellently suited as additives to animal feeds. It is anobject of the present invention to produce a soapstock of low moisturecontent, typically in the range of 25-40% moisture and preferably lessthan about 30% moisture.

'In my prior application Serial Nor. 481,930, `filed January 14, 1955, lhave disclosed a process employing soda ash in low excesses and inamount insufiicient to suppress the evolution of carbon dioxide, thecarbon dioxide being removed iin a chamber in which the pressure wasabove atmospheric. While that process has many advantages as comparedwith the older dehydration-rehydration or high-excess processes, it hasbeen found that even better results can be obtained by adjusting theoperating conditions and equipment to maintain a slight vacuum in thechamber in which the carbon dioxide is separated. Experience withexcesses of 2.5 to 3 times has shown that removal of carbon dioxideunder slight pressure is diiiicult on oils having afree fatty acidcontent of 1.8% or higher, such a process tending to produce aneffluentJ oil unduly high .in impurities, eg., containing more than 0.2%free fatty acids, and an effluent soapstock unduly high in free oil,e.g., containing upwards of 15-20% free oil. Re-refining of such eluentoils with caustic soda produces unduly high saponilication andentrainrnent losses. When treating crude oils containing 2.0% or morefree fatty acids, it is most diicult to obtain effluent oils containingless than 0.2% free fatty acids when separating the carbon dioxide underslight pressure, although the operation becomes quite feasible with thepresent process. For the most efiicient and desirable operations, theeluent oil should contain not more than 0.1% free fatty acids, `whetheror not it is subsequently rerefined, and the present process makes thiscommercially possible.

lIt is an object of the present invention to mix with a glyceride oil anamount of fsocla ash insuicient to prevent evolution of carbon dioxide,and 'to separate theV carbon dioxide from the resulting oil-soapstockmixture under a slight vacuum. Another object of the invention is tomaximize the removal of carbon dioxide While minimizing the removal ofwater from the-oil-soapst'ock mixture.

ln the preferred practice of the invention, the amount of water left inthe mixture is sufficient to produce a centrifugally separablesoapstock. If a part of the water is removed with the carbon dioxideenough may not remain to solubilize and make separable the soapstock,thus resulting in soapstock entrainment in the separated oil. Also,removal of a part of the water with the carbon dioxidewould tend tocreate a foam in the degasser unless all of the Water is removed, whichis undesirable in the low excess process exemplified. l

I-t has been `found possible, in accordance with the present invention,to obtain the advantages of low-excess operation while avoiding theneedv for rehydration. This has been made possible by separation ofcarbon dioxide under such vacuum conditions as will remove all of thecarbon dioxide albeit without any significant dehydration.

The carbon dioxide that is liberated when using soda ash in low excessmustbe rather completely removed if it is not to interfere withseparation in the centrifuge.

If the carbon dioxide is removed from the mixture while under slightpressure, there is a tendency for some `of the carbon dioxide to remaindissolved in the oil and to be liberated at any lower pressure existingin the centrifuge. By use of the present process and apparatus theremoval of the carbon dioxide is morefcomplete, leading to betterseparation and to other improvedresults.

Unless all of the carbon dioxide is removed, the reaction between thesoda ash and the acidic impurities will not go to completion. This isparticularly impor` tant in processes employing soda ash in low excess.It is difficult to remove all of the carbon dioxide and force thereaction to completion if the carbon dioxide is separated undersuperatmospheric pressure. However, by separating under a slight vacuumthe carbon dioxide can be substantially completely removed to permit thereaction to go to completion.

The removal of the carbon dioxide in accordance with the presentinvention destabilizes and defoams the oilsoapstock mixture or emulsion.While it has been previously known that such an emulsion could bedestroyed by evaporating the water, the present invention makes itpossible to destabilize the mixture or emulsion even while the moistureis present. The resulting mixture will thus separate better and willproduce substantially improved products.

If the carbon dioxide is separated under pressure, there is an increasedtendency to form acid soaps which are quite soluble in the oil. Suchacid soaps have a tendency to form when limited amounts of soda ash areused and result from the combining of one molecule ofsodium soap with afatty acid molecule. If the carbon dioxide is removed completely, as byseparating under the slight vacuum as herein contemplated, there is lesslikelihood of difficulty from such acid soap either because less of itforms or because if formed it tends to be broken by the complete removalof the carbon dioxide.

In accordance with the invention, the effectiveness of removal of thecarbon dioxide is also facilitated by spreading the oil-soapstockmixture on a surface as a lm. It is an object of the present inventionto spread such a mixture on the internal surface of a degasser containerto facilitate the complete separation of carbon dioxide therefrom.During flow along such a surface the separation is made more completebecause of the thinness of the lm, the increased area of the mixtureexposed to the gaseous atmosphere, and theincreased time of exposure tosuch atmosphere into which the carbon dioxide may escape.

' A further object is to spread the mixture on a heated surface in suchmanner as to maximize the separation of carbon dioxide while minimizingthe removal of moisture.

n the other hand, the degasser of the invention is useful in a widevariety of other processes where it is desired to separate gases,including vapors, from a liquid. In this respect, it is an object of theinvention to provide a degasser in which a stream of the incoming liquidis spread uniformly along a surface, preferably the internal surface ofa container, this surface being adjustable in temperature by beingjacketed. A further object is to apply the liquid to'an upright surfacein successive sweeps so timed that a substantially uniform film of theliquid ows downwardly along the surface by gravity while exposed to theadjacent atmosphere within'the container. A further object is to spreadthe liquid on an internal wall of a container maintained under a vacu-The degasser of the invention provides different processing zones inwhich different temperatures can be maintained. 1n addition, it is Welladapted to the handling of effluents of a heavy or viscous character andprovides an effluent withdrawal means effectively sealing the containerand permitting continuous withdrawal of the effluent irrespective ofpressure conditions within the container'. lt is an object of theinvention to provide a degasser having one or more such features.r

Further objects and advantages of the invention will be evident to thoseskilled in the art from the following descriptilon of the exemplaryembodiments, including those suggested in the attached drawing in which:

Fig. 1 is a pipeline diagram of an apparatus for the continuous refiningof glyceride oils, illustrating the degasser in vertical section;

Fig. 2. is a horizontal sectional view taken along the line 2 2 of Fig.1; and

Fig. 3 is a fragmentary view of one of the nozzles of the degasser,taken as indicated by the arrow 3 of Fig. 2.

Referring particularly to Fig. l, the exemplary apparatus includes,generally described, a proportioning-heating means 10, a degasilier 11and a separating means 12. This apparatus is adapted to rene a glycerideoil withdrawn from a tank 18 by a proportioning pump 19 which delivers astream thereof through a heater 20 to a mixer 21. Similarly, a solutionof soda ash may be withdrawn yfrom a tank 22 by a proportioning pump 23which forces the stream through a heater 24 and through a pipe 25 whichmay discharge directly into the mixer 21 or, as

shown, to a pipe junction of a pipe 26 which feeds the mixer. In thisway, the soda ash solution preliminarily mixes with the oil at such apipe junction before entering A the mixer 21.

The mixer 21 may be of any suitable type which will thoroughly andintimately mix the soda ash solution with the oil. However, whenpracticing the low excess soda ash process herein disclosed, the sodaash solution should be intensely and rapidly mixed with the oil in themixing step. Batch mixing in large kettles is not effective in suchprocess and it is desirable to use mechanical mixing of proportionedstreams continuously delivered to a rotary mixer. The mixer 21 may be ofthis type and the mixing action therein should be so intimate that thereagent is thoroughly consumed.

The excess of soda ash solution is under the control of theproportioning pumps 19 and 23, which can be driven by a motor 27connected to one of the pumps through a speed-change device 28.Similarly, the motor 27 may drive, through a speed-change device 29 anauxiliary proportioning pump `30 to be later mentioned.

The oil-soapstock mixture issuing from the mixer 21 is advanced underthe pressure of the proportioning pumps through a heater 32 and thenceto the degasiiier 11 through a pipe 33. The heaters 20, 24 and 32, aswell as similarly-shown heaters to be later mentioned, may be' of thetype including a pipe coil 34 disposed in a housing 35 through which anydefined heating medium is circulated by means of pipe connections 36.

The time of mixing or the time of contact before reaching the degasser11 is not critical. It is usually def sirable, however, that this timeof contact be at least about three minutes, measured from the initialmixing to the time of discharge into the degasser. This time of contactmay be provided by the mixer 21 and the heater 32. Should it be desiredto further increase this time of contact or additionally to adjust thetemperature of the oil-soapstock mixture before delivery to the degasser11, a valve 38 in the pipe 33 may be closed to divert the flow through anow-open valve 39 in a pipe 4t) leading to a mixer 41 which maydischarge through a heater 42'l before returning the flow to the pipe 33beyond the valve 38.

If it is desired to introduce the soda ash solution in two portions, asis sometimes beneficial, a` rst portion is introduced through the pump23 and a second portion may be withdrawn from the tank 22 through avalve 45, being proportioned Vby the auxiliary pump 30. The resultingstream may be delivered through a heater 46 to a pipe 47 which joins thepipe 40 ahead of. the mixer 41. In this way the second portion ofthesoda ash solution can be mixed with the previously formed oil-soapstockmixture advancing in the pipe 40, the mixer 41 serving to mix the secondportion of the solution, the temperature of the mixture being adjustedby the heater 42 ifk this is desired.

The degasser 11 includes a generally upright container 50 supported by asuitable framework 51. Bln the preferred construction, the container 50is divided into several jacketed sections arranged for rapid temperatureadjustment of the internal liquid if this is desired. As shown, thecontainer 50 includes an upper section 53, a tapered section 54 and alower section 55.

The upper section 53 is cylindrical, being closed by a head 57. -Itprovides an inner circular surface 58 surrounded by a jacket 59 whichmay be filled with any suitable fluid through pipes 60. Additional pipes61 circulate a liquid medium through a coil 62 within the jacket. Thismedium is usually a heating medium.

The incoming stream, exemplified as an oil-soapstock stream containingcarbon dioxide, is conducted to the interior of the container 50.through a pipe 64 connected to a head 65 which supplies the liquid tothe interior of a pipe 66 through holes 67 therein. lThe pipe 66 isrotatably mounted in the head 65 and in a bearing 68 outside thecontainer, being driven by bevel gears 69 from a gearreduction orvariable speed motor 70. The lower end of the pipe 66 carries a T 71from which arms 72 extend, these arms being shown as having curved endsproviding nozzles 73. This structure represents a rotary distributorwhich distributes the incoming liquid as a lm on the heated circularsurface 58. The nozzles 73 move in recurring paths immediately adjacentthe inner circular surface 58 and provide orifices which discharge theliquid at a velocity approximately the same as the lineal or peripheralvelocity of the moving nozzles. Discharge at a slightly higher velocityis preferred. The moving nozzles deposit the liquid on the surface 58 incontact with a previously-supplied portion of the liquid', applied tothe surface on a previous fractional rotationof the distributor butwhich has moved by gravity along the surface since being initiallyapplied thereto. By controlling the rate of rotation in this manner, acontinuous film of the liquid is formed, this film gravitating along itssupporting surface 58 and being exposed to the atmosphere at the centerof the container 50. In the exemplified process, this atmosphere ispredominantly carbon dioxide which has separated from such film.

The construction of the nozzles 73 to obtain the desired filming actionis not critical. As shown in Figs. 2 and 3, these nozzles are formed byflattening and sidewardly cutting the ends of the pipes 72 to providehorizontally elongated openings 74 facing and moving close to thecircular surface 58. If desired, a spreader plate 75 may be secured tothe pipe ends, providing an arcuate surface 76 facilitating the desiredspreading action. In other instances, spray type nozzles may be employedinstead of the spreader-type nozzles illustrated.

As previously mentioned, it is desirable in the exemplified process thatthe carbon dioxide be separated from the oil-soapstock mixture under aslight vacuum. This slight vacuum can be produced by forcefullywithdrawing the carbon dioxide from the upper section 53 of thecontainer 50, using a suitable pump, blower or fan 80 connected to thecontainer by a pipe 81. A dry-type vacuum pump .can be employed and itis sometimes feasible to employ merely' a fan or blower to yexhaust thecarbon dioxide at a sufiicient rate to maintain the desired slightvacuum. One or more sight glasses 82 may be mounted in the head 57,permitting internal inspection of the degasser during operation.

The iilm flowing down the heated circular wall 58 reaches a conical wall85 of the tapered section 54, fiowing therealong until it joins a body86 of the liquid. During such fiow along the conical wall, the film maybe rapidly heated or cooled or it may be merely maintained at theexisting temperature. This is made possible by use of acorrespondingly-tapered jacket 87 providing a space which can be filledwith any suitable liquid through pipes 88, the space containing a coil89 through which a heating or cooling medium may be circulated by use ofthe pipes 90 shown.

The lower section 55 of the degasser 11 comprises a cylindrical housing92 surrounded by a jacket 93 equipped with a coil 94 to heat or cool thesurrounding liquid, introduced through pipes 95, thus heating or coolingthe eiuent liquid or mass moving. downwardly within the housing 92. Suchdownward movement is induced by turning a conveyer screw 96 fittingsnugly within the cylindrical housing 92 and journalled by bearings 97and 98 to turn about the central axis of this housing. The bearing 98may be mounted in a suitable cross-member 100 of the framework 51 at aposition below the housing 92. The lowermost end of this housing isclosed by a plate 101 carrying a packing gland 102 which seals thecentral shaft of the conveyer screw 96. This central shaft is preferablya pipe 105 driven by a motor 106 through suitable gearing 107.

To increase the heat-transfer action of the lower section 55, a heatingor cooling medium may be circulated internally of the screw conveyer 96.Such a medium may be supplied under pressure to a pipe which provides aconstricted portion 111 traversing a chamber 112 formed by a manifold113. The constricted portion 111 is joined with a pipe 115 smaller inexternal diameter than the internal diameter of the pipe 105. Theuppermost end of the smaller pipe 11S opens on the interior of thelarger pipe 105 near the bearing 97. Liquid forced through the pipe 110thus rises in the smaller pipe 115 and returns in the annular spacebetween the two pipes, collecting in the chamber 112 from whence it isremoved through a pipe 116.

The internal and external heating or cooling of the liquid or mass to bewithdrawn produces a very flexible operation, particularly if used inconjunction with the variable speed motor 106. The viscosity of theliquid can be rapidly adjusted by change in temperature, the viscosityand the speed of rotation of the conveyer screw 96 determining thepumping action exerted on the liquid or mass being drawn downwardly inthe housing 92 and discharged from the lower end thereof through a pipe117. Indeed, it is possible continuously to withdraw liquids from thedegasser against even a high-vacuum therein while still maintaining theinterior of the container sealed from the atmosphere.

In the exemplified low-excess soda ash process, the mixture of oil andsoapstock, free of carbon dioxide but substantially unreduced in watercontent, flows through the pipe 117 under the control of a valve 118therein. 'The temperature may be further adjusted by flow through a heatexchange device 119 before entering the separating means, exemplified asa centrifuge 120 representative of a bank thereof usually employed incommercial processes. In the exemplified process, each centrifuge may beof the conventional type operating at atmospheric pressure. In certaincircumstances, however, it may be of the closed or pressure typeeffecting centrifugal operation under super-atmospheric pressure. Ineither event, it separates the mixture into streams of oil and soapstockrespectively discharging through pipes 121 and 122. A rather thicksoapstock will often be produced by the low excess soda ash processherein exemplified. If aV thinner soapstock is desired, water or aqueoussolutions can be added just ahead of or within the centrifuge 120 as bybeing supplied through a pipe 124 to the zone of separation to dischargewith the soapstock. Such aqueous solutions may act as diluting,weighting or soapstocksoftening agents but are ordinarily not needed inthe preferred practice of the invention.

Exemplifying further the low excess soda ash process of the invention, Iprefer to use excesses of 1.5-2 times the amount theoretically requiredto react with the acidic impurities of the oil. In some instances,excesses up to 3 times can be employed in practicing such process. Useof the lowest possible excesses of soda ash is sometimes important fromthe standpoint of decreased costs. For example, some 360 lbs. of sodaash can be saved in refining a tank car of oil containing 2.1% freefatty acids when employing an excess of 1.5 times, as compared with a 3times excess. However, the use of the lowest feasible excess isdesirable for other reasons such as reducing the volume of thesoapstock; lowering the refining loss of oil through occlusion in thesoapstock; production of soapstock of improved quality for certainimportant uses, including uses as feed additives; reduced evolution ofcarbon dioxide which must be withdrawn; etc.

Typically soda ash solutions of -26" B. are employed in the exemplifiedprocess, a 20 B. solution being common. The strength of the solution isdetermined in part by the desired moisture to be in the soapstock at thetime of separation, if no additional moisture is added and if there isno dehydration in the degasser 11.

It is usually desirable that the temperatures in the upper section 53 ofthe degasser 11 be elevated, e.g. G-210 F. A large part of this heat isdesirably supplied ahead of the degasser. In this connection the oil andreagent streams may be preheated if desired in the heaters 20, 24 or 46before being mixed. The mixture can be further heated in the heaters 32and 42 or one or both of these heaters can be employed to supply all ofthe heat ahead of the degasser.

The surface 58 on which the mixture is filmed is desirably at atemperature somewhat above that of the, oil-soapstock mixture expelledby the rotating nozzles 73. At the same time, if there is to be nosignificant dehydration of the mixture in the degasser, the temperatureof the surface 58 should not exceed the boiling point of water at theslight vacuum existing in the degasser. Often the temperature of theliquid in the jacket S9 may be close to or slightly above. such boilingpoint, being sometimes as high as 250 F. if there is to be significantheating in the degasser. It is beneficial to the complete removal of thecarbon dioxide from the mixture that this mixture be spread as a thinfilm on a heated surface. already at the desired elevated temperature,the jacket 59 may be used to keep the surface 58 at the same temperatureto prevent chilling in the upper section 453 of the degasser 11.

The wall temperature in the tapered or intermediate section 54 of thedegasser may be equal to, higher or lower than in the upper section 53.Equality of such temperatures is often used in the low-excess soda ashprocess although it is possible to use the higher wall temperatures inthe section 54 if there is to be progressive heating in the degasser.

In the lower section 55 of the degasser the defoamed and decarbonatedmixture is kept mixed by the screw 96. The temperature here depends inpart upon the desired viscosity of the mixture to be discharged as aneffluent, also upon the degree of heating or cooling desired at thisstage before separating the soapstock. In some instances, improvedoperation results from a sudden chilling of the mixture in the lowersection 55 even though it may be desirable to further heat the mixturein the heater On the other hand, if the incoming mixture is 119 beforethe centrifugal separation, which will usually q be in a range of16o-220 F., typically 180-210 F. if centrifugal separation in 'the usualatmospheric-pressure centrifugals is effected.A However, if desired,such separation can take placev in centrifuges of the closed or pressuretype discharging streams of oil and soapstock under superatmosphericpressure, the pressure increase from the degasser to the centrifugesbeing produced by the screw conveyor effluent means of the degasser orby an auxiliary pump in the pipe 117. i

In practicing the low-excess soda ash process, a slight vacuum ismaintained in the upper interior or central zone of the degasser so thatthe carbon dioxide separates from the film of the mixture atsubatmospheric pressure. In the absence of substantial throttling of themixture in the nozzles 73 this slight vacuum may extend back into thepipe 64. The slight vacuum in the degasser 11 is usually about .5-10" ofmercury, preferably 1-4" of mercury.

When processing certain oils of high gum content, it is sometimesnecessary to increase the amount of soda ash above the amount that wouldbe used on an otherwise corresponding oil of low gum content. Withhighgum oils some of the soda ash appears to be absorbed by the gums soas not to be available for reaction with the free fatty acids, and thisshould be taken into account before selecting the low excesses on thebases herein disclosed and claimed.

The degasser 11 of the invention finds utility in processes other thanthe low-excess soda ash process herein exemplified. Thus, for example,it can be used with the medium or high-excess soda ash processes eitheras a substitute for presently used dehydrators in thedehydration-rehydration process or to remove carbon dioxide which mayresult from improper mixing of higher excesses of soda ash with a crudeoil, particularly with oils of high free fatty acid content. When usedas a substitute for the present dehydrators in thedehydrationrehydration process, the degasser has the outstandingadvantage of reducing the likelihood of priming because of suddenchanges in vacuum. For example, one of the primary sources of suchpriming is a sudden change in vacuum from, say, 28.5 to 15 of mercury asa result of cooling water failure or reduced flow in the steam ejectorsystem normally employed to maintain the vacuum. Upon restoration of thehigh vacuum, part or all of the contents of the conventional dehydratormay be sucked out of the chamber. When using the present degasser atsuch high vacuum, such priming is eliminated. This effect is aided inpart by the large internal zone of the degasser and the distance betweenthe body 86 and the pipe 81 leading to the vacuum pump.

The degasser 11 may also be used for quickly and effectively dryingdegummed oils or oils that have been water washed following degurnmingor alkali refining. Some crude cottonseed oils are sensitive to colorsetting and treatment thereof can be improved by removing the waterunder vacuum during flow as a film along cooled internal surfaces of thedegasser, e.g., either the inner surface 58 or the conical wall 85. Adry, quick-cooled degummed cottonseed oil produced in this fashion isstable and when subsequently refined with caustic soda will produce arefined oil of light color which will not revert.

When the degasser is used in high-vacuum processes, the verticaldispostion of the sections and the versatility and rapidity with whichtemperature changes can be effected will be found lto make possibleimproved operation. Also, the internally jacketed screw conveyor 96makes possible a rapid heat transfer with the material moving downwardwithin the degasser. This screw conveyor can be employed to Withdraw aviscous eliiuent continuously even under high-vacuum conditions withinthe degasser.

Various changes and modifications can be made with- 2,917,525 outdeparting from the spirit of the invention as defined being insufficientto suppress the evolution of carbon in the appended claims. dioxide,thus forming an oil-soapstock mixture containc aim as my invention: ingcarbon dioxide and water; moving a stream of said the presence of waterunder conditions producing an oiloxide from the mixture; withdrawingsubstantially all of soapstock mixture containing Carbon dioxide andWater, the carbon dioxide from said chamber in substantially the amountof soda ash being insufiicient to prevent formoisture-free condition;withdrawing a mixture of oil mation of carbon dioxide in the mixture;removing the l and soapstock containing water from said chamber; andcarbon dioxide from the mixture in the absence of subcentrifuging thesoapstock of the withdrawn mixture from stantial dehydration of themixture while the mixture is the oil thereof, under vacuum; and thensubjecting the resulting mixture 7. A process as defined in claim 6including the step to a separating action to separate the soapstock fromof regulating the withdrawal of carbon dioxide and the the oil.withdrawal of the oil-soapstock mixture from said charn- 2. A processfor refining glyceride oils containing ber to develop aslightvacuum theein. acidic impurities including free fatty acids, which process 8process as dennen rn Clarm 6 rn Wlnch sard Cham. includes the steps ofmixing soda ash with said oil in ber as an upright circular surface andan adjacent nozzle e presence of water under conditions producing anoiland in which said stream is formed into a m fiowing soapstock mixturecontaining carbon dioxide and water, along said surface by moving saidnozzle in a recurring the amount 0f sede ash eine insuilicient t0Prevent fcrpat inside and adjacent said upright circular surface mationof Carbon CllOXlCle 1n the niiXture, reInOVlng the at a given linealvelocity while discharging the stream carbon dioxide from the mixture inthe absence of subof mixture therefrom at a velocity nearly equal tosaid Stantial dehydration of t e mixture by lowing the mixgiven linealvelocity to coat the circular surface with a ture along e `surface Whilesubjecting the liOWing nliXture film of the mixture, the carbon dioxideseparating from the Presence 0f Water under ccnditicns prcduciug anOiltlie mixture into contact with a portion of the mixture scepstccknliXture ccnttlining cnrbOn diOXide and Water, applied to said circularsurface on a previous sweep of t e ernOunt 0f seda ash beinglnsuiliclent t0 Pr event fcrthe nozzle to form a continuous film of themixture gravimation of carbon dioxide in the mixture, removing therating along suon surface,

carbon dioxide from the mixture in the absence of subl0, A process forrenning those crude glyceride oils Stantial dehydration of the mixtureby Spreading the mixcontaining at least 1.8% free fatty acids, whichprocess ture as a film On a heated Surface t0 free the carbon includesthe steps of: mixing soda ash with said oil in belOW the boiling Peint0f Water; and then subjecting the 40 about 2.5-3 times that requiredtheoretically to react said A PrOeeSS fOr refining glyceride Oils.containing mixture in the absence of any substantial amount of includeSthe Steps Of: mixing With the Oil an amount 0f 45 at a temperature belowthe boiling point of Water; and

soda ash less than three times the amount thereof theooenrrrfugrne theresulting mixture wlnle of a composition retically required toneutralize said acidic impurities to snbsrantrally the saine as producedas a result of said Produce an Oll-scelstcck InlXture ccntelnlng carbondi* vacuum treatment to separate therefrom a soapstock oxide and water;removing the carbon dioxide from the comprising said Soaps, mixturewhile the mixture is un er vacuum but while avoiding any substantialdehydration of the mixture; and References Cited in the file of thispatent then separating the soapstock from the mixture.

process as defined in claim 4 in which the soap- UNITED STATES PATENTSstock is centrifugally separated from the mixture while 1,297,333 EarlMar. 18, 1919 the latter contains an amount of water commensurate2,614,656 Clark et al. Oct. 21, 1952 with but not substantially lessthan the amount of water 2,620,894 Peterson et al. Dec. 9, 1952 in thecarbon-dioxide-containing mixture. 2,686,796 Markley et al Aug, 17, 19546. A process for refining glyceride oils containing 2,710,664 Blackmoreer al June 14, 1955 acidic impurities including free fatty acids, whichprocess 2,748,884 Erwin June 6, 1956 includes the steps of: mixingsaid'oil with an amount of 60 2,759,957 Thurman Aug. 2l, 1956 soda ashno more than three times the amount thereof 2,769,827 Clayton Nov. 6,i956y theoretically required to neutralize said acids, said amountDedication 2,917,525.Benjame'/n H. Thurman, New York, NY. PROCESS FORREFINING GLYCERIDE OILS. Patent dated Dec. 15, 1959. Dedication filedRefining, Unineonpomed. Hereby dedcates to the publie the terminal partof the term of said patent effective December 31, 1963.

[Oee'al Gaeette September Q9, 1.964.]

June 30, 1964, by the assignee, Benjamin Clayton, doing businesses'

1. A PROCESS FOR REFINING GLYCERIDE OILS CONTAINING ACIDIC IMPURITIESINCLUDING FREE FATTY ACIDS, WHICH PROCESS INCLUDES THE STEPS OF: MIXINGSODA ASH WITH SAID OIL IN THE PRESENCE OF WATER UNDER CONDITIONSPRODUCING AN OILSOAPSTOCK MIXTURE CONTAINING CARBON DIOXIDE AND WATER,THE AMOUNT OF SODA ASH BEING INSUFFICIENT TO PREVENT FORMATION OF CARBONDIOXIDE IN THE MIXTURE; REMOVING THE CARBON DIOXIDE FROM THE MIXTURE INTHE ABSENCE OF SUBSTANTIAL DEHYDRATION OF THE MIXTURE WHILE THE MIXTUREIS UNDER VACUUM; AND THEN SUBJECTING THE RESULTING MIXTURE TO ASEPARATING ACTION OT SEPARATE THE SOAPSTOCK FROM THE OIL.